1. Field of Invention
This invention belongs to recreational snowmobile vehicles particularly the ones having one or more skis, and particularly snow ski provided with at least a wear runner and also a blade. This patent proposes a modification to the blade to increase the ski response in soft snowy path to procure an aggressive driving. Furthermore, the invention comprises a modification to a central runner which is self sharpening.
2. Description of the Prior Art
The present invention is an improvement over four inventions from the same inventor so being utilized by other snowmobile skis comprising the same essential characteristics: at least a wear runner and at least a blade. The prior patents from the same inventor which the present invention refers to are the following:    CA 2,388,833; Snowmobile runner.    CA 2,378,638; Snowmobile ski auto-stabilizer, in M or reversed W.    CA 2,388,801; Concave ski stabilizer.
CA 2,300,359 and U.S. Pat. No. 6,520,512; snowmobile ski stabilizer comprising a reversed U channel and a Teflon™ corrector lining the web of the U-channel to provide smooth gliding of the snow between the wings of the U-channel. Centrally of the wings is disposed an existing carbide runner which may be replaced by a self adjusting runner.
A review of the prior art revealed the following patents:    U.S. Pat. No. 5,344,168 Olson Sep. 6 1994; shows a wear runner 50 provided with a carbide bar 56 of the shape of a triangular diamond. The carbide resists until its point 58 is worn more than 10% after which time it does not behave with sufficient sharpness to engage itself into sharp ice, whence the danger of side swaying, the sharp point being dull from wear and incapable of stopping swaying.    CA 2,195,166; shows a wear runner 26 supported in 64, 66, 68 but without added carbide. The element which does the cutting is a break blade 152 which again when dull may no longer cut into the ice.    U.S. Pat. No. 6,012,728; is a snowmobile ski with multiple protruding keels on its underside. The height of the steering keel gradually increases in protrusion, from front end to a central position and may reduce from central position to aft end, but is not high enough to really penetrate snow.OBJECTIVES
During fast turns of snowmobile skis comprising at least one wear runner and one blade, the snow pressure increases because of the presence of a central wear runner. This phenomenon creates a tendency to lift up the ski during high speed turns. The objective of the present invention is to provide an exit door to the snow by making an aperture in the blade opposite the runner The snow submitted to pressure from the runner gets out by the aperture and the ski no longer tends to lift up by excessive snow pressure. Meanwhile, the adherence of the blade during fast turns and the driving are so improved under these circumstances. To make this aperture useful it must be made oppositely to the wear runner. The wear runner refers to a runner supporting the ski and the snowmobile during passages over a hard surface. The wear runner is obligatory lower than the blade. During passage on a hard surface it is the wear runner that gets into contact with the ground, not the bottom of the blade. The aperture in the blade must be made oppositely to the wear runner otherwise if the blade were to touch a hard surface at a spot (for example a railroad track), the blade would get stuck in the aperture. Being opposite to the wear runner, the edges of the aperture do not touch the hard surface for it is the wear runner which is in contact with the hard surface. A second objective of the invention is that the wear runner be self sharpening, more particularly comprising a rectangular central blade embedded at the center of a support also rectangular and having parallel sides, the hardness of the support being inferior to the hardness of the blade so when the blade slides over a hard surface such as asphalt road, the support is prevented from wearing as long as the carbide resists. During passage in abrasive paths, the support wears more rapidly than the central carbide leaving a difference in height between the blade and the support over all the depth of the wear runner, making it self sharpening, always at a same degree, until the end of the wear out of the runner.